The proposed research aims to study the purified Ca2 ion pumping ATPase from human erythrocyte membranes, both in the solubilized and reconstituted forms. The reconstituted ATPase will be utilized for studies of calcium transport. Aims of the project include study of the composition of the purified ATPase, study of its enzyme kinetics and mechanism, and concurrent studies of Ca2 ion transport and Ca2 ion ATPase. The project also aims to use antibodies against the Ca2 ion ATPase to estimate the amount present in erythrocyte membranes. The radioimmunoassay which has been developed for the Ca2 ion ATPase of erythrocyte membranes will be utilized to estimate the amount of Ca2 ion ATPase present in the plasma membranes of other cell types.